SCIENTIFIC
Renal Abscess Complicated by Renal Vein Thrombosis Mimicking Clinical Stage T3a Renal Cell Carcinoma
AUTHORS : Eric M . Bonar , MD 1
Chad E . Morley , MD 2 Hilary E . Morley , MD 3 Linda S . Nield , MD 4
1
West Virginia University School of Medicine
2
Department of Urology , West Virginia University School of Medicine
3
Department of Pediatrics , West Virginia University School of Medicine
4
Department of Medical Education , West Virginia University School of Medicine
CASE PRESENTATION
ABSTRACT
A 71-year-old woman presented with worsening polyuria , urinary urgency , and decubitus ulcers . The patient ’ s past medical history included Type II diabetes mellitus , hyperlipidemia , hypothyroidism , hypertension , congestive heart failure , recurrent urinary tract infections ( UTIs ), and urinary incontinence . Significant findings on examination revealed a body mass index of 38.98 kg / m 2 and severely erythematous decubitus ulcers in her sacral area with an erythematous and edematous left lower extremity from foot to mid-thigh . Lower extremity Doppler ultrasound was performed to rule out deep vein thrombosis and was negative . Significant laboratory findings included a serum creatinine level of 1.85 mg / dL , blood glucose of 746 mg / dL , blood lactate of 6 mmol / L , and anion gap of 21 . Inflammatory markers were elevated with a white blood cell count of 14.4 x 10^3 / uL , and c-reactive protein level of 145.1 mg / L . Urinalysis was remarkable for glucose > 500 mg / dL , protein 30 mg / dL , red blood cell count > 182 / high powered field ( HPF ), white blood cell count > 182 / HPF , ketones 5 mg / dL , and negative nitrites . An abdominal and pelvic computerized tomography ( CT ) scan revealed a mass ( 2.3 cm x 3.1 cm ) in the mid-portion of the right kidney with contrast enhancement areas of heterogeneity , and a thrombus in the right main renal vein ; the radiologic features were highly suggestive of clinical stage T3a renal cell carcinoma ( Figure 1a and 1b ). A biopsy of the mass was not performed due to the patient ’ s extensive co-morbidities . Greater than 100,000 colonies of Escherichia coli ( E . coli ) grew in her urine culture , and she was treated with linezolid , metronidazole , and cefpodoxime . Anticoagulant therapy consisting of heparin bridging over to warfarin was continued for RVT and for deep vein thrombosis prophylaxis . The patient returned to baseline health and was discharged after a three-week admission . Repeat CT imaging approximately eight weeks later revealed complete resolution of the RVT and renal mass , with no signs of infarction ( Figure 2a and 2b ). No new suspicious enhancing renal masses or hydronephrosis were present .
DISCUSSION
We present a 71-year-old woman with multiple chronic medical conditions , ultimately diagnosed with a renal abscess complicated by RVT that initially mimicked clinical stage T3a RCC . Patients with infection and hypercoagulable states , including nephrotic syndrome and malignancies , are at risk of developing renal vein thrombosis ( RVT ). 1 In the United States , cancers of the kidney and renal pelvis are fairly common . The incidence rates of kidney cancer are
Renal abscesses accompanied by a renal vein thrombosis ( RVT ) may have a similar appearance to clinical stage T3a renal cell carcinoma ( RCC ) on computed tomography ( CT ) imaging . RVTs are rare clinical findings that more commonly occur in adults with malignant renal tumors or nephrotic syndrome . A 71-year-old woman with risk factors for both renal infection and RCC was found to have a heterogeneous mass with irregular borders and areas of contrast enhancement on CT imaging . A two-week course of antibiotic and anti-coagulant treatment was prescribed with close follow-up . Urine culture eventually grew greater than 100,000 colonies of Escherichia coli . Repeat imaging after six weeks revealed resolution of the mass and the RVT . This patient ’ s case emphasizes that although the findings of RVT and renal mass more commonly point to the diagnosis of malignancy , infections may present in a similar manner but require substantially different treatment . Close follow-up with repeat imaging is imperative to differentiate malignancy from infection or other causes .
22.1 % and 10.9 % for men and women , respectively , with a median age at diagnosis of 64 years . 2 Renal cell carcinoma ( RCC ) is the most common primary malignancy of the kidney accounting for more than 90 % of cancers of the kidney . 3 Although rarely reported in the medical literature , RVT is also a potential complication of severe acute pyelonephritis . 4 Additional complications of acute pyelonephritis , such as intrarenal abscesses , must be considered in patients with underlying anatomical abnormalities , renal stones , and diabetes mellitus .
Assimakopoulos et al . reported a case of a patient with pyelonephritis due to an E . coli infection that was associated with perirenal abscess and ipsilateral renal vein thrombosis on CT imaging , successfully treated with anti-microbials and an anti-coagulant . 4 Seven more cases of RVT in patients with acute pyelonephritis were reported by Yildiz , Halil , et al . Three of the seven patients had E . coli positive urine cultures , with a mean age of approximately 59 years . 5 These rare cases , including our patient , illustrate that bacterial infections resulting in a renal abscess can have similar characteristics to a neoplastic mass . 6 Renal abscesses with RVT can have similar findings on CT to RCC . The mass can appear to be heterogenous with irregular borders and areas of contrast enhancement . 7 TNM staging of RCC provides the most important prognostic information
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